A cordless telephone system comprising a base unit, at least one handset, and one or more expansion units is provided. The handset and the expansion units communicate with the base unit via communication channels implemented in a wireless communication protocol. The expansion units can provide the system with communication interfaces to various external networks, such as an additional analog telephone line, a digital telephone line, or a cellular telephone. Conference calling functionality is provided between handsets and expansion base units within the primary base unit. Data services can also be provided by a wireless expansion base unit.